Structure of LED of high heat-conducting efficiency

ABSTRACT

A structure of LED of high heat-conducting efficiency is to provide a copper substrate having a plurality of indentations. An insulating layer is formed on the surface of the substrate and the bottom of the indentations. Meanwhile, a set of metallic circuits is formed on the insulating layer of the substrate, and a layer of insulating lacquer is coated on the surface of the metallic circuits, where there is no electric connection and no enclosure. A tin layer is coated on the insulating layer of the indentation and the metallic circuits, where there is no insulating lacquer. Furthermore, a set of light-emitting chips are die bonded on the tin layer of the indentation. Next, the light-emitting chips and the metallic circuits are electrically connected by a set of gold wires. Moreover, a ringed object is arranged on the surface of the substrate, such that the light-emitting chip set, the gold wires and the metallic circuits are enclosed therein. Meanwhile, a fluorescent glue is attached to the light-emitting chip set, the gold wires and the metallic circuits. Eventually, an epoxy resin is filled into the interior of the ringed object to be dry for forming an epoxy resin layer. Thus, a packaging manufacture of LED is completed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to an LED, in particular, to astructure of LED of high heat-conducting efficiency.

2. Description of Prior Art

Light-emitting diode (LED) is a semiconductor component in solid state,which applies an inter-combination of electron and hole to releaseenergy in a form of light. LED belongs to luminescence lighting and hasmany merits, such as: small size, long life, low electricityconsumption, quick reaction speed, and vibrating endurance. Basically,LED is a light-emitting component for a variety of appliance,information-showing board, and communicating product.

As shown in FIG. 1 and FIG. 2 (i.e. ROC Patent M292879), when atraditional LED is manufactured, a metallic plate 100 is firstly stampedinto a lead frame 101, which is placed into a die together with ametallic base 103. After injection formation, two electrode legs 102 ofthe lead frame 101 and a partial area of the base 103 are enclosed andfixed by the glue seat 104, making base 103 and two electrode legs 102located in an indentation 105 of the glue seat 104. Next, thelight-emitting chip 106 is die-bonded onto the surface of the base 103by means of silver glue, and the light-emitting chip 106 and twoelectrode legs 102 are electrically connected by gold wires 107.Finally, after a fluorescent glue body 108 is attached to thelight-emitting chip, an epoxy resin 109 is further filled into theindentation 105 of the glue seat 104.

However, the above manufacturing steps of LED are so tedious that theyconsume too many working time and labor, making it being impossible tolower down the manufacturing cost. According to the prior manufacturingmethod of LED, a light-emitting chip 106 is firstly pasted onto a base(or lead frame) by means of silver glue, then the positive and negativeelectrodes of the light-emitting chip 106 are connected to the electrodelegs 102 by means of wiring machine with gold or aluminum wire, finallyan epoxy resin 109 is applied to complete the packaging procedure.However, since the poor physical characteristics of electrode legs 102,base 103, and epoxy resin 109 in terms of heat conduction, heatresistance reaches as high as 250° C./W˜300° C./W in this traditionalpackaging form. Therefore, the temperature of LED will rise due to thepoor heat dissipation, consequently causing the deterioration and ageingof the epoxy resin 109. In a long term, the light-emitting efficiency ofthe LED will be decreased and the temperature increment will beaccelerated, because of the thermal accumulation. A poor reliabilityphenomenon is caused by a structure stress generated from thetemperature increment.

Accordingly, aiming to solve aforementioned shortcomings, after asubstantially devoted study, in cooperation with the application ofrelatively academic principles, the inventor has at last proposed thepresent invention that is designed reasonably to possess the capabilityto improve the prior arts significantly.

SUMMARY OF THE INVENTION

The invention is mainly to provide a simple structure and manufacturingmethod for solving the drawbacks of traditional method in manufacturingLED, thus that its manufacturing cost is lowered down. According to theinvention, first of all, a copper metal is provided as a substrate, ofwhich tin thickness applied as die bond is controlled around 4˜5μ,aiming to reducing thermal resistance of heat transfer, promotingcooling effectiveness, increasing using life of light-emitting chip, andpreventing deterioration of materials.

Secondly, the invention is to provide a packaging method of LED of highcooling efficiency and a structure thereof. First of all, a coppersubstrate having a plurality of indentations is provided. Then, aninsulating layer is formed on the surface of the copper substrate andthe bottom of the indentations. Furthermore, a set of metallic circuitsis formed on the insulating layer of the copper substrate. Again, alayer of insulating lacquer is coated on the surface of the circuit set,where there is no electric connection and no enclosure. Meanwhile, a tinlayer is coated on the insulating layer of the indentation and thesurface of the metallic circuit set, where there is no insulatinglacquer. Next, the light-emitting chip set is die-bonded on the tinlayer of the indentation. Subsequently, the surfaces of thelight-emitting chip set and the metallic circuit set are electricallyconnected by a set of gold wires, making the light-emitting chip setformed an electrical connection in series. Moreover, a hollow ringedobject is arranged on the surface of the copper substrate, such that thelight-emitting chip set, the gold wires, and circuits are enclosed inthe ringed object. Afterwards, a fluorescent glue is attached to thelight-emitting chips, the gold wires, and the metallic circuits, suchthat a fluorescent layer is formed. Finally, an epoxy resin is filledinto the interior of the ringed object to enclose the fluorescent layer.After the epoxy resin is dry, an epoxy resin layer is formed. Thus, apackaging manufacture of LED is completed.

BRIEF DESCRIPTION OF DRAWING

The features of the invention believed to be novel are set forth withparticularity in the appended claims. The invention itself, however, maybe best understood by reference to the following detailed description ofthe invention, which describes a number of exemplary embodiments of theinvention, taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is an outer appearance illustration of a lead frame and a glueseat of a traditional LED;

FIG. 2 is an illustration of a completely packaged LED in FIG. 1;

FIG. 3 is a flowchart for illustrating the manufacturing steps of an LEDaccording to the present invention;

FIG. 4 is an outer appearance illustration of a substrate according tothe present invention;

FIG. 5 is an illustration of circuits formed on the surface of asubstrate according to the present invention;

FIG. 6 is a die-bonding illustration of the circuits on the surface of asubstrate according to the present invention;

FIG. 7 is an explosive illustration of a ringed object and a substratesurface having circuits and light-emitting chips with gold wiresaccording to the present invention;

FIG. 8 is a perspective illustration of the outer appearance of asubstrate surface arranged a hollow ringed object according to thepresent invention;

FIG. 9 is a side-sectional view of FIG. 8;

FIG. 10 is an illustration showing that fluorescent glue is attachedover the structure shown in FIG. 9;

FIG. 11 is an illustration showing that an epoxy resin is attached overthe structure shown in FIG. 10;

FIG. 12 is a perspective view explosively illustrating anotherpreferable embodiment of an LED according to the present invention; and,

FIG. 13 is a top view illustrating an assembly of another preferableembodiment of an LED according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In cooperation with attached drawings, the technical contents anddetailed description of the present invention are described thereinafteraccording to a number of preferable embodiments, being not used to limitits executing scope. Any equivalent variation and modification madeaccording to appended claims is all covered by the claims claimed by thepresent invention.

Please refer to FIG. 3 and FIG. 4, which respectively are amanufacturing flowchart and a substrate's outer appearance illustrationof an LED according to the present invention. As shown in these figures,when an LED of the invention is packaged and manufactured, first of all,in step 100, a copper substrate 1 is provided, on which a plurality ofindentations 11, positioning holes 12 and “U” shape openings 13 arearranged.

In step 102, please refer to FIG. 4 together. An insulating layer 14having heat-conducting effect is formed on the surface of the coppersubstrate 1 and the bottom of the plural indentations 11.

In step 104, please refer to FIG. 5 together. A set of metallic circuits15 is formed on the insulating layer 14.

In step 106, please refer to FIG. 6 together. An insulating lacquerlayer 16 is coated on the surface of the metallic circuit set 15, wherethere is no electrical connection and without being enclosed, and theinsulating lacquer layer 16 is white, so the metallic circuits 15 may beprevented from oxidation.

In step 108, please refer to FIG. 6 together. A tin layer 17 having athickness of 4˜5μ is sprayed on the surfaces of the insulating layer 14of the indentations 11 and the surfaces of the metallic circuits 15,where there is no insulating lacquer 16 in a way, such that the thermalresistance of heat conduction is small and an excellentheat-transferring efficiency is provided.

In step 110, please refer to FIG. 7 together. A set of light-emittingchips 2 is die-bonded on the tin layers 17 of the plural indentations11.

In step 112, please refer to FIG. 6 together. The surfaces of thelight-emitting chip set 2 and the tin layers 17 on the metallic circuitset 15 are connected by a set of gold wires 3 in a way, such that aconnection in series is formed among the light-emitting chips 2.

In step 114, please refer to FIGS. 7, 8, 9 together. A hollow ringedobject 4 is placed on the positioning holes 12 on the surface of thecopper substrate 1 and encloses the set of light-emitting chips 2, thegold wires 3, and the metallic circuits 15.

In step 116, please refer to FIG. 10 together. Some fluorescent glue isattached to the set of light-emitting chips 2, the gold wires 3, and themetallic circuits 15 within the ringed object 4, where there is noinsulating lacquer 16 coated.

In step 118, please refer to FIG. 11 together. Some epoxy resin 6 isfilled into the interior of the ringed object 4 and encloses thefluorescent layer 5. After the epoxy resin layer 6 is dry, a protectinglayer is thus formed. Finally, the formation of an LED is completed byconnecting a plurality of light-emitting chips in series.

Please refer to FIG. 7 and FIG. 8 again. An LED structure of theinvention mainly includes: a substrate 1, a set of light-emitting chips2, a set of gold wires 3, a ringed object 4, a fluorescent layer 5, andan epoxy layer 6.

According to a preferable embodiment of the invention, the coppersubstrate 1 is a circular body, on which a plurality of indentations 11are arranged. A plurality of positioning holes 12 are arranged bysurrounding the indentations 11, while a plurality of “U” shape openings13 are arranged at the circumferential edges of the copper substrate 1.In addition, an insulating layer 14 is formed on the surface of thecopper material 1 and the bottoms of the indentations 11. A set ofmetallic circuits 15 is arranged on the insulating layer 14 andincludes: a first circuit section 151, a second circuit section 152, athird circuit section 153, and a fourth circuit section 154. A layer ofinsulating lacquer 16 is coated on the surfaces of the metallic circuitset 15, where there is no electrical connection and without beingenclosed by the fluorescent layer 5. Furthermore, a tin layer 17 withthickness of 4˜5μ is coated on the insulating surfaces 14 of theindentations 11 and the surfaces of the metallic circuits 15, wherethere is no insulating layer 16.

The light-emitting chip set 2 includes a first, second, thirdlight-emitting chips 21, 22, 23, which are die-bonded on the tin layers17 of the plural indentations 11.

The gold wire set 3 includes a first gold wire 31, a second gold wire32, a third gold wire 33, a fourth gold wire 34, a fifth gold wire 35,and a sixth gold wire 36, in which the first circuit section 151 and thepositive pole of the first light-emitting chip 21 are electricallyconnected by the first gold wire 31, the second circuit section 152 andthe negative pole of the first light-emitting chip 21 are electricallyconnected by the second gold wire 32, the second circuit section 152 andthe positive pole of the second light-emitting chip 22 are electricallyconnected by the third gold wire 33, the third circuit section 153 andthe negative pole of the second light-emitting chip 22 are electricallyconnected by the fourth gold wire 34, the third circuit section 153 andthe positive pole of the third light-emitting chip 23 are electricallyconnected by the fifth gold wire 35, finally, the fourth circuit section154 and the negative pole of the third light-emitting chip 23 areelectrically connected by the sixth gold wire 36. Thereby, the first,second, third light-emitting chips 21, 22, 23 are electrically connectedin series.

Please refer to FIG. 9. In this case, the ringed object 4 is a hollowring body 41 made of metallic or plastic materials. A positioning part42 is projected from the bottom of the ring body 41 and is positioned tothe positioning holes 12. In addition, the inner wall of the ring body41 is inclined to form a reflecting face 43, which is capable offocusing the light beams generated from the light-emitting chips 2 andreflecting and projecting them outwardly.

Please refer to FIG. 10. In this case, the fluorescent layer 5 is madeof material of fluorescent glue, which encloses the surface of a set ofthe light-emitting chip 2, the gold wires 3, and the metallic circuits15, where there is no insulating lacquer 16 coated, thus a fluorescentlayer 5 being formed.

Please refer to FIG. 11. In this case, the epoxy resin layer 6 is madeof epoxy resin and packages the fluorescent layers 5 within the ringbody 31 in a way, such that an epoxy resin layer 6 capable of protectingthe fluorescent layer 5 and sets of the light-emitting chips 2, the goldwires 3, and the metallic circuits 15 is formed.

When the LED structure is used, a positive power source is connected tothe first circuit section 151, while a negative power source isconnected to the fourth circuit section 154, so the first, the second,and the third light-emitting chips 21, 22, 23 are lighted. The lightbeams will be focused and projected outwardly, since the first, thesecond, and the third light-emitting chips 21, 22, 23 are die-bonded tothe bottoms of the indentations 11 via the tin layer 17 of a thicknessof 4˜5μ. Because the thickness is only 4˜5μ, its thermal resistance isless than that of a silver glue commonly used. Furthermore, when heat isconducted downwardly, since the thermal resistance of the coppersubstrate 1 is less than those of sapphire and alumina if they are usedas a supporting substrate, so the heat sources generated from the first,the second, and the third light-emitting chips 21, 22, 23 can betransferred to the copper substrate 1 rapidly for processing a coolingprocedure. Under such arrangement, the using life of the light-emittingchip 2 can thereby be prolonged.

Please refer to FIG. 12 and FIG. 13, which respectively are aperspective explosive view and an assembled top view of anotherpreferable embodiment of an LED according to the present invention. Asshown in these figures, the structure of this embodiment is roughly sameas that of above embodiment described in FIG. 4 through FIG. 11. Theonly difference is that there are more light-emitting chips 2A, whichare electrically connected in a circular series by means of gold wiresets 3A and metallic circuits 15A. In this case, the light beamsprojected outwardly will be brighter.

Summarizing aforementioned description, the invention is a novelstructure for LED indeed, which may positively reach the expected usageobjective for solving the drawbacks of the prior arts, and whichextremely possesses the innovation and progressiveness to completelyfulfill the applying merits of new type patent, according to which theinvention is thereby applied. Please examine the application carefullyand grant it as a formal patent for protecting the rights of theinventor.

However, the aforementioned description is only a number of preferableembodiments according to the present invention, being not used to limitthe patent scope of the invention, so equivalently structural variationmade to the contents of the present invention, for example, descriptionand drawings, is all covered by the claims claimed thereinafter.

1. A structure of LED of high cooling efficiency, including: a coppersubstrate, on which a plurality of indentations are arranged, aninsulating layer being arranged on a surface of the copper substrate andon a bottom of the indentation, a set of metallic circuits beingarranged on the insulating layer of the copper substrate, an insulatinglacquer being arranged on surfaces of the metallic circuit set, wherethere is no electric connection and no enclosure, a tin layer beingarranged on a surface of the insulating layer of the indentation and onsurfaces of the metallic circuit set, where there is no insulatinglacquer. a set of light-emitting chips, which is die-bonded on the tinlayer of the indentation; a set of gold wires, by which the metalliccircuit set and the light-emitting chip set are electrically connected;a ringed object, which is arranged on the substrate to enclose themetallic circuit set, the light-emitting chip set, and the gold wirestherein; a fluorescent layer, which is arranged within the ringed objectand over the surfaces of the metallic circuit set, the light-emittingchip set, and the gold wires; and an epoxy resin layer, which isarranged within the ringed object and over the surfaces of thefluorescent layer.
 2. The structure of LED of high cooling efficiencyaccording to claim 1, wherein the copper substrate in is a circularbody, on which a plurality of positioning holes are arranged to surroundthe indentations, and at a circumferential edge of which a plurality of“U” shape openings are arranged.
 3. The structure of LED of high coolingefficiency according to claim 2, wherein the metallic circuit set iscomprised of a plurality of circuit sections.
 4. The structure of LED ofhigh cooling efficiency according to claim 1, wherein the light-emittingchip set is comprised of a plurality of light-emitting chips.
 5. Thestructure of LED of high cooling efficiency according to claim 1,wherein the insulating lacquer is white.
 6. The structure of LED of highcooling efficiency according to claim 1, wherein the ringed object ismade from one material of metal or plastic.
 7. The structure of LED ofhigh cooling efficiency according to claim 6, wherein a bottom of thering body has a positioning part, which is projected outwardly and ispositioned to positioning holes of the copper substrate, and wherein aninner wall of the ring body is inclined for forming a reflecting face.8. The structure of LED of high cooling efficiency according to claim 1,wherein the thickness of the tin layer is about 4˜5μ.